Common shampoo ingredients include special detergents that trap the dirt on hair without stripping away natural oils. Other ingredients may include acids, lather builders, thickeners, conditioners, and fragrances. In the United States, the Food and Drug Administration (FDA) requires that shampoo manufacturers accurately list the ingredients on the bottle. In listing ingredients, manufacturers usually use the chemical names for many of these shampoo ingredients.
Soaps and compounds that trap dirt are commonly called detergents or surfactants. The chemical name for the detergent usually used in shampoo is ammonium lauryl sulfate. Some shampoos contain a similar compound called sodium lauryl sulfate. These detergents bond to the oils in your hair and allow them to be washed away in the water.
Many detergents are alkaline or base compounds, which can make the hair look dull. Therefore, many shampoo manufacturers include acids that help keep hair looking shiny. The most commonly used acids in shampoo include ascorbic acid and citric acid. A form of ascorbic acid is Vitamin C, and citric acid is the natural acid found in such fruits as lemons and oranges.
While acids help keep the hair shiny, shampoo also needs to lather to better clean the hair. The lather builders traditionally included in shampoo ingredients are called cocamide mea or cocamidopropyl betaine. These chemical compounds help create the suds, which make the detergents work better by allowing more dirt to be lifted from the hair and washed away.
In addition to lather builders, most shampoos contain ingredients that make the product thick. Thickening ingredients help keep the shampoo at the right consistency, ensuring a product that is thick and creamy. The chemical names for thickeners include xanthan gum, cetyl alcohol, sodium chloride, and stearyl alcohol. Many of these chemical compounds also act as conditioning agents on the hair. Conditioners help make the hair shafts softer, smoother, thicker, and stronger. Other conditioners that many shampoo manufacturers add are allantoin, glycerin, and glycerin. Shampoo for dry hair or damaged hair might have more of these conditioning ingredients.
Typically companies add other shampoo ingredients to encourage customers to buy their hair products. Specialty shampoos, such as baby shampoo, curling shampoo, dandruff shampoo, and other types of shampoos contain additional additives. Many shampoos advertise ultraviolet light protection, proteins, vitamins, plant extracts, and other organic ingredients. The most common sunscreen used in shampoos is octyl salicylate, and some use PABA, a compound found in sunscreen lotions.